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location University of Copenhagen
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Jan
26
awarded  Nice Answer
Jan
25
answered Certain signed sum over $S_n$
Jan
25
comment Exactness of pure functors
To be explicit, a functor which is the identity on pure objects but is not exact is given by mapping $V \stackrel f \to W$ to $\ker(f) \stackrel 0 \to \mathrm{coker}(f)$. Another possible fix than Jeremy Rickard's suggestion might be to impose the condition that the functors $\mathrm{gr}^W_i$ are exact. (This is just a suggestion, I don't know if the lemma holds under either added hypothesis.)
Jan
22
answered Isomorphism between a mapping class group and the fundamental group of a moduli space
Jan
21
answered Étale cohomology versus classical cohomology
Jan
15
revised What is the value of this hyperelliptic Hodge-type integral?
added 31 characters in body
Jan
14
revised What is the value of this hyperelliptic Hodge-type integral?
added 268 characters in body
Jan
14
answered What is the value of this hyperelliptic Hodge-type integral?
Jan
14
answered Mod 2 Totaro spectral sequence for non-orientable manifolds
Jan
14
answered cohomology version of Cartan-Leray spectral sequence that deduces cup product
Jan
8
comment How large must $A$ be if $\{1, \ldots, N\} \subseteq A-A$?
Why the votes to close??
Jan
8
comment Reference for “multi-monoidal categories”
I believe that what you're after is Max Kelly's notion of a club; there is a club whose pseudo-algebras are precisely monoidal categories, and if you unravel the definition of being a pseudo-algebra for this club you should get what you wrote above.
Jan
6
awarded  Enlightened
Jan
6
awarded  Nice Answer
Jan
3
reviewed Close equivalence in simplicial category
Jan
3
reviewed Leave Open Is it possible on an elliptic curve both $x,y$ to be arbitrary large powers infinitely often?
Dec
29
revised Unifying Geometry for Characteristic Classes
added 8 characters in body
Dec
26
answered cohomology of an intermediate extension of a local system
Dec
21
comment Blow-ups of $\mathbb{P}^{n-3}$ and $(\mathbb{P}^1)^{n-3}$
Maybe you know this, but maybe it can be helpful. (It's not an answer.) The space $\overline M_{0,n}$ can be obtained from $\mathbf P^{n-3}$ by a sequence of blow ups, where the first step is blowing up at $(n-1)$ points in general position. This is in Kapranov, "Chow quotients of Grassmannian I". It can also be obtained by iterated blowing up of $(\mathbf P^1)^{n-3}$ where the first step is blowing up at the three points you picked. This is in Tavakol, "The Chow ring of the moduli space of curves of genus zero".
Dec
20
comment What's so special about $1$-categories?
The general rule of thumb appears to be that the prevalence of $n$-categories is very rapidly decreasing as a function of $n$ (except for the special case $n=\infty$). Indeed, ordinary sets are vastly more common in day-to-day mathematics than categories, in the sense that an average mathematics paper will contain a significantly larger number of different sets than categories. Categories are in turn vastly more common than 2-categories, and so on. In the other direction, truth values are more common than sets.